Zeolite-containing silica-alumina hydrogel catalyst and method of making same

ABSTRACT

A specially prepared zeolite-containing silica-alumina hydrogel gives a catalyst that is attrition resistant, more active catalytically, more selective and more stable. The hydrogel is prepared by steps including nozzle mixing of reactants to form a hydrogel, ion exchanging with ammonium, aluminum and rare earth ions, washing, drying and impregnating with rare earths.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a division of copending application Ser. No. 732,553, filed Oct.15, 1976.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a crystalline aluminosilicatezeolite-containing silica-alumina cracking catalyst and to a method ofpreparing same. More particularly, it relates to such catalyst that ismade attrition resistant, more active, selective and stable by stepscomprising forming a hydrogel, wet processing and homogenizing same,spray drying and rare earth impregnation.

2. Discussion of the Prior Art

Cracking catalysts are solid materials that have acidic properties.Because of the nature of the reactions taking place, the catalyst musthave high porosity. Furthermore, since the catalyst circulates rapidlybetween reaction zones and burning, or regeneration zones, it must alsohave resistance to abrasion, temperature changes and the like.

Natural catalysts are composed principally of silica and alumina, butthey contain certain other materials which may be harmful under certaincircumstances. The synthetic silica-alumina materials are generally madefrom pure materials so that many of the shortcomings of the naturalmaterials have been overcome. However, the catalysts made usingsilica-alumina prepared by prior art processes are subject to excessiveattrition, aging and loss of activity and selectivity. The invention asdescribed hereinafter has not been described or suggested in any priorart of which applicants are aware.

SUMMARY OF THE INVENTION

The invention provides a cracking catalyst comprising a silica-aluminahydrogel made by the steps comprising:

(1) nozzle-mixing of an acid alum stream comprising an aqueous solutionof aluminum sulfate and sulfuric acid with a second stream comprising anaqueous solution of sodium silicate, an alkali metal hydroxide andsuspended fines;

(2) passing the resulting sol to a dispersing devise to form dropletsand causing these droplets to gel;

(3) exchanging the gel by contacting same, in order, with (a) anammonium salt solution, (b) an aluminum salt solution and (c) a rareearth salt solution;

(4) washing with water;

(5) homogenizing;

(6) spray drying;

(7) impregnating with rare earth ions;

(8) drying.

The invention also provides a method of making the catalyst and aprocess for using the catalyst in the cracking of hydrocarbons.

In the above, alkali metal is preferably sodium.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Silica-alumina catalysts have been known for many years and aregenerally divided into those prepared for use in FCC units and those foruse in TCC units. The fluid cracking catalysts are often prepared tocontain an active crystalline zeolite, the balance being clay oramorphous silica-alumina. They are prepared as microspheroidal particlesand generally contain from about 12 to about 28% of the activecrystalline zeolite. The catalysts of this invention will contain fromabout 5 to about 30%, by wt., of the total catalyst of the zeolite.Total fines in the catalyst will be between about 40% and about 60% bywt.

There are several problems inherent in cracking catalysts made by theprocesses of the prior art. As has been touched on previously these aremainly attrition and loss of activity and selectivity. We have found aprocess for preparing catalysts via all-embracing silica-aluminahydrogels which provides catalysts that overcome the stateddisadvantages of prior art catalysts.

In the first step of the process of this invention, an acid alumsolution and a sodium silicate stream containing a substantial portionof fines are pumped to a mixing nozzle where they mix to form a sol.This is one of the critical aspects of this invention. If the desiredadvantage of attrition resistance is to be attained, the reactants mustbe nozzle-mixed.

The "acid alum" is an aqueous solution of sulfuric acid and aluminumsulfate. The sodium silicate solution contains waterglass, and sodiumhydroxide. The composition of the forming stream is adjusted so that thedesired gel composition is obtained with a favorable gelation time. Thefines used comprise finely dispersed kaolin clay, calcined rare earthexchanged zeolite Y and recycle fines from the spray dryer (final stepin this process).

The second step of the process requires forming gel droplets. The sizeof such droplets will range from about 0.1 mm to about 15 mm. This stepis not critical and may be accomplished by forming droplets in theconventional way, i.e., by dropping the sol through oil where it gels,or by passing the sol as it comes from the nozzle to a rotating disc,from which small droplets spin off and gel while falling through air.While the step is not, per se, critical, it is believed that certainadvantages are to be gained by air-forming droplets by use of a spinningdisc. Thus, it is believed that easier processing of the hydrogel ispermitted. Ion exchange and washing of the hydrogel rather than of thespray-dried gel is for best attrition resistance.

We prefer to use air forming, which, under the preferred conditions ofthe instant process, yields beads of approximately 1 mm in diameter.Typically, a cylindrical forming chamber was used. A spinning disc witheither a flat or a concave surface may be employed, and the speedthereof will range between 200 and 1500 rpm. Optimum conditions forforming 0.2 to 1 mm diameter spheres were found to be 1000 rpm with a4-inch disc with the forming streams preheated to 90°-92° F. Such airforming of beads is an expedient method for producing small bead sizessuitable for wet processing on a filter.

The third process step is a critical one in that the advantages arerealized only if the sequence of exchange is (1) exchange with ammoniumions, (2) exchange with aluminum ions and (3) exchange and/orimpregnation with rare earth ions. The anions associated with theammonium, aluminum and rare earth cations may be any that are easilyremoved from the gel by washing. These include the sulfate, nitrate andchloride ions. In this step, at least 60% of the original cation shouldbe removed.

When using the rotating disc to form gel beads, the gel may drop fromthe rotating disc through air into a gel aging tank containing thedesired concentration of ammonium salt in solution, usually around 2% inwater, for the first exchange. The concentration is not critical, andmore or less salt may be used.

Following the ammonium ion exchange, the slurry of beads is dewatered inthe first section of a compartmented belt filter and ion exchanged withan aluminum salt solution. The preferred concentration of aluminum saltin solution is about 1.5%, since it has been shown that little is gainedfrom using higher strength solutions.

Upon completion of the aluminum ion exchange, the product is washed withwater and then exchanged with rare earth ions by contacting with asolution of a rare earth salt, e.g., the chloride. Conditions thereinare conventional, since the method of rare earth exchange in and ofitself is not critical. This exchange is followed by washing with waterto remove any free salts.

The hydrogel is homogenized, as for example, by being passedsequentially through a Charlotte Mill and a Manton-Gaulin homogenizer.The viscosity is adjusted by addition of water and the material is driedcounter-currently in a spray dryer. The product is reslurried with arare earth salt solution, as for example, a rare earth chloridesolution, contacted for 15 minutes to 5 hours or more, and dewatered. Itis then slowly dried in a conventional dryer.

When rare earth ions are mentioned, it will be understood that such willbe contained in a salt or a mixture of salts wherein the anion can be achloride, nitrate or acetate. The rare earth ion may be, for example,cerium, lanthanum, praseodymium, meodymium, samarium and yttrium.Furthermore, mixtures of rare earth salts can be used.

With reference to the exchange steps, we do not wish to be bound by anytheory, but we do offer the following as one explanation of why (in ouropinion) the sequence is a critical one. It is believed that theporosity of the catalyst particles is adjusted in the ammonium ionexchange step by controlling the degree to which the gel continues tocross-link after gelling. The porosity in them influences the activityand particularly the selectivity of the catalyst. The step of exchangingwith the aluminum ion, besides removing the sodium ion, increases theattrition resistance by further cross-linking the partially orcompletely aged gel. Rare earth exchange imparts superior steamstability to the finished product, and by placing into the catalyst, byimpregnation, such a high percentage of RE₂ O₃, one gets a catalysthaving superior catalytic selectivity.

The preferred catalyst comprises, as already mentioned, an all-embracinggel. By this is meant a hydrogel matrix which embraces all the fines tobe incorporated in the catalyst. That is, at the instant of formation,there is no separable water phase present as it is in the case ofprecipitates, including hydrous oxide precipitates.

The suspended fines called for in step (1) of the Summary include one ormore crystalline aluminosilicate zeolites, as for example, rare earthexchanged Y-zeolite. Such fines also include inorganic solids that haveno effect on the cracking action of the catalyst but whose presenceincreases the attrition resistance of the final catalyst. Among theselatter solids can be mentioned alumina and kaolin clay. In addition,recycle fines from the spray drying step may be used.

It should be mentioned that the steps of exchanging, spray drying,impregnating and drying are conventional and well known in the art. Forexample, typical ion exchange procedures are described in U.S. Pat. Nos.3,140,249; 3,140,251 and 3,140,253. Such procedures comprise contactingthe zeolite with a salt of the desired replacing ion at from about 40°F. to about 120° F. Drying temperatures may range from about 150° F. toabout 600° F.

Having described the invention in general terms, the following examplesare offered as illustrations thereof.

EXAMPLE 1

    ______________________________________                                        Acid Alum:  87.58% H.sub.2 O                                                               0.75% Al.sub.2 (SO.sub.4).sub.3                                              11.67% H.sub.2 SO.sub.4  (100%)                                               Spec. Gravity at 60° F.:                                                1.087 g/cc                                                       Silicate                                                                      solution:   95.82% waterglass (8.9% Na.sub.2 O                                            28.7% SiO.sub.2)                                                               4.18% NaOH (100%)                                                Fines-Silicate                                                                Forming Stream:                                                                           55.41% silicate solution                                                       1.52% H.sub.2 O                                                              10.45% of 30% REY (3% Na) slurry                                              14.29% of 55% Georgia kaolin slurry                                           18.33% of 15% recycle (ball-milled) slurry                        ______________________________________                                    

All slurries were stabilized with 0.6% Marasperse N before mixing. Therecycle used contained 12% REY.

Acid alum and fines-silicate were preheated to 95° F. and nozzle-mixedat the rate of 390 cc of fines-silicate per minute to 335 cc of acidalum per minute. The fines-silicate were passed through the innerorifice (0.031"). The acid alum was passed through the outer orifice.The sol pH was 9.1-9.2.

The sol was directed onto a spinning disc and sprayed into a chamber.When the droplets reached the bottom of the chamber, they had gelled.The gel was collected in water, then exchanged for 2 hours withsufficient 2.1% (NH₄)₂ SO₄ solution to cover the gel. The ammoniumexchange was followed by nine exchanges with 1.5% Al₂ (SO₄)₃ solutionfor 1/2 hour each. After washing with water for at least 7 hours, thegel particles were covered with a 1.2% RECl₃.6H₂ O (RE=rare earthmixture) solution for a 3-hour treatment. Finally, the gel was washedchloride-free.

The gel was formed by passing it through a colloid mill (Charlotte Mill)and a Manton-Gaulin homogenizer with sufficient water added to produce agel slurry of the correct consistency for spray drying. The spray-driedmaterial contained 0.14% Na, 2.86% RE₂ O₃ and 13.0% H₂ O.

For impregnation, 3000 g of the spray-dried catalyst was slurried with amixture of 526 g of 50% RECl₃.6H₂ O solution and 3330 g H₂ O and stirredfor 12 hours. The slurry was then filtered, but not washed, and dried at250° F. for 40 hours.

The catalysts of the other examples were prepared by similar procedures:

EXAMPLE 2

Acid alum and silicate solutions had the same composition as in Example1.

Fines-silicate forming stream:

53.36% silicate solution

0.46% H₂ O

10.67% of 30% REY (3% Na) slurry

15.74% of 55% Georgia kaolin slurry

19.76% of 15% recycle (ball-milled) slurry

Acid alum and fines-silicate were preheated as before and nozzle-mixedat the rate of 270 cc of fines-silicate and 217 cc of acid alum perminute. The sol pH was 9.2-9.3. The spherical gel particles obtained byspraying the sol with a spinning disc of 6" diameter were collected in2.1% (NH₄)₂ SO₄ solution, where they remained for 2 hours. The ammoniumexchange was followed by nine 1/2-hour exchanges with 1.5% Al₂ (SO₄)₃solution, 7 hours of water wash and a 2-hour exchange with 1.2%RECl₃.6H₂ O solution as in Example 1. The procedure for homogenizationand spray-drying was the same as in Example 1. The spray-dried materialcontained 0.10% Na, 2.47% RE₂ O₃ and 13.8% H₂ O. The impregnationprocedure was also the same as in Example 1.

EXAMPLE 3

Acid alum and silicate solutions had the same composition as in Example1.

Fines-silicate forming stream:

53.36% silicate solution

0.44% H₂ O

13.34% of 30% REY (3% Na) slurry

13.09% of 60% Georgia kaolin slurry

19.76% of 15% recycle (ball-milled) slurry

The recycle contained 15% REY.

Acid alum and fines-silicate were nozzle-mixed at the rate of 390 cc offines-silicate and 327 cc of acid alum per minute; the inner orifice was0.036". Collection and base-exchange of the gel was done in the samemanner as in Example 2, except that the rare earth chloride solutioncontained 1.5% RECl₃.6H₂ O because of the higher REY content of the gel.The procedure for homogenizing and spray-drying was the same as inExample 1. The spray-dried material contained 0.10% Na, 3.15% RE₂ O₃ and12.3% H₂ O. Impregnation was done in the same manner as in the priorexamples.

EXAMPLES 4 to 6

Acid alum and silicate solutions had the same composition as in Example1.

Fines-silicate forming stream:

53.36% silicate solution

11.06% H₂ O

14.82% of 30% REY (3% Na) slurry

20.75% of 50% Georgia kaolin slurry Acid alum and fines-silicate werepreheated to 92° F. and at a rate of 755 cc of fines-silicate and 640 ccof acid alum per minute. The gel pH was 9.1. The gel was sprayed with a4" disc, processed, homogenized and spray-dried in the same manner as inExample 3, except that the ammonium exchange lasted only 1 hour. Thespray-dried material contained 0.11% Na, 3.27% RE₂ O₃ and 20.0% H₂ O.

The catalyst was impregnated to three different RE₂ O₃ levels byagitating the catalyst in a RECl₃ solution for 30 minutes.

    ______________________________________                                        Examples          4        5        6                                         ______________________________________                                        Wt. of catalyst, g                                                                              2000     2000     2000                                      Wt. of H.sub.2 O, g                                                                             2305     2220     2135                                      Wt. of 50% RECl.sub.3  . 6H.sub.2 O, g                                                           180      350      520                                      ______________________________________                                         The impregnated catalysts were dried at 250° F. as before.        

EXAMPLE 7

The gel of this example was prepared in the same manner as in Examples4-6. The ammonium exchange was extended to 2 hours. Otherwise, the wetprocessing, homogenizing and spray-drying were the same as in Example4-6. Impregnation was done as in Example 5.

EXAMPLE 8

The gel of this example was prepared in the same manner as in Examples4-6. The gel was collected in water. There were no ammonium exchange,only nine 1/2-hour exchanges with 1.5% Al₂ (SO₄)₃ solution. Furtherprocessing was identical to Examples 4-6. The spray-dried materialcontained 0.09% Na, 3.54% RE₂ O₃ and 13.1% H₂ O.

For impregnation, 3000 g of this catalyst was slurried with a mixture of3300 g H₂ O and 500 g of 50% RECl₃.6H₂ O solution and stirred for 30minutes. The slurry was then filtered, but not washed, and dried at 250°F.

The composition and the cracking activity of the above products aresummarized in Table 1. The charge stock used in the cracking runs wasDurban Fresh Feed, described in Table 2.

                                      TABLE 1                                     __________________________________________________________________________    Example     1   2   3   4   5   6   7   8   A.sup.(5)                                                                         B.sup.(5)                     __________________________________________________________________________    REY, wt. %.sup.(1)                                                                        11.85                                                                             12  15  15  15  15  15  15  --  --                            Georgia Kaolin, wt. %.sup.(1)                                                             30.6                                                                              33  29.7                                                                              35  35  35  35  35  --  --                            Gel Matrix, wt. %.sup.(1)                                                                 57.55                                                                             55  55.3                                                                              50  50  50  50  50  --  --                            Na, wt. %   0.13                                                                              0.10                                                                              0.10                                                                              0.08                                                                              0.11                                                                              0.10                                                                              0.12                                                                              0.07                                                                              0.84                                                                              0.27                          RE.sub.2 O.sub.3, wt.%                                                                    6.84                                                                              7.01                                                                              7.21                                                                              5.66                                                                              8.08                                                                              9.51                                                                              7.28                                                                              6.52                                                                              0.13                                                                              --                            Apparent Density, g/cc                                                                    0.62                                                                              0.73                                                                              0.70                                                                              0.72                                                                              0.73                                                                              0.73                                                                              0.69                                                                              0.80                                                                              0.84                                                                              0.73                          Pore Volume, cc/g.sup.(2)                                                                 0.68                                                                              0.68                                                                              0.66                                                                              0.64                                                                              0.64                                                                              0.64                                                                              n.d.                                                                              0.38                                                                              0.47                                                                              --                            Cracking Activity .sup. (3)                                                   Cat/Oil     2.98                                                                              3.03                                                                              2.99                                                                              2.95                                                                              3.00                                                                              2.95                                                                              2.96                                                                              2.98                                                                              2.99                                                                              2.99                          WHSV        8.38                                                                              8.22                                                                              8.34                                                                              8.43                                                                              8.30                                                                              8.43                                                                              8.41                                                                              8.35                                                                              8.34                                                                              8.32                          Temperature, °F.                                                                   962 960 958 953 953 946 958 951 956 949                           Conversion, vol. %                                                                        73.7                                                                              72.2                                                                              74.4                                                                              76.7                                                                              75.2                                                                              73.4                                                                              75.8                                                                              76.1                                                                              79.7                                                                              68.5                          C.sub.5.sup.+  Gasoline, vol. %                                                           60.8                                                                              59.6                                                                              60.1                                                                              60.3                                                                              60.3                                                                              61.3                                                                              59.9                                                                              60.3                                                                              60.4                                                                              56.5                          C.sub.4 's vol. %                                                                         15.0                                                                              14.4                                                                              15.2                                                                              16.6                                                                              16.0                                                                              14.2                                                                              17.3                                                                              16.5                                                                              17.6                                                                              14.4                          Dry Gas, wt. %                                                                            7.9 7.8 7.9 8.5 8.3 7.4 8.0 8.1 9.4 6.8                           Coke, wt. % 2.81                                                                              2.40                                                                              3.15                                                                              4.47                                                                              3.60                                                                              2.82                                                                              3.72                                                                              4.21                                                                              6.41                                                                              3.18                          After Severe Steaming.sup.(4)                                                 Cat/Oil     2.99                                                                              --  3.00                                                                              --  2.99                                                                              --  2.98                                                                              --  2.99                                                                              2.99                          WHSV        8.32                                                                              --  8.30                                                                              --  8.32                                                                              --  8.35                                                                              --  8.34                                                                              8.34                          Temperature, °F.                                                                   950 --  956 --  959 --  956 --  949 948                           Conversion, vol. %                                                                        67.2                                                                              --  73.4                                                                              --  71.4                                                                              --  70.6                                                                              --  64.2                                                                              59.5                          C.sub.5.sup.+  Gasoline, vol.%                                                            56.0                                                                              --  60.4                                                                              --  59.5                                                                              --  56.3                                                                              --  54.7                                                                              48.0                          C.sub.4 's vol. %                                                                         12.8                                                                              --  14.6                                                                              --  13.2                                                                              --  14.8                                                                              --  13.2                                                                              12.6                          Dry Gas, wt. %                                                                            6.7 --  7.9 --  7.4 --  7.8 --  5.9 6.0                           Coke, wt. % 2.74                                                                              --  2.72                                                                              --  2.88                                                                              --  3.27                                                                              --  2.63                                                                              2.86                          __________________________________________________________________________     .sup.(1) composition of insolubles before wet processing                      .sup.(2) before impregnation                                                  .sup.(3) after 4 hr. steaming at 1400° F. with 100% steam at           atmospheric pressure                                                          .sup.(4) 4 hr. steaming at 1475° F. with 100% steam at atmospheric     pressure                                                                      .sup.(5) commercial catalysts having a crystalline aluminosilicate as the     active ingredient.                                                       

                  TABLE 2                                                         ______________________________________                                        COMPOSITION AND PROPERTIES OF CHARGE STOCK                                    ______________________________________                                        API Gravity             24.2                                                  Aniline Point, °F.                                                                             182.3                                                 Pour Point, °F.  90                                                    Conradson Carbon, wt. % 0.21                                                  Ramsbottom Carbon, vol. %                                                                             0.28                                                  Sulfur, wt. %           2.12                                                  Total Nitrogen, wt. %   0.097                                                 Basic Nitrogen, ppm     268                                                   Hydrogen, wt. %         12.39                                                 Kinematic Viscosity at 100° F.                                                                 52.58                                                 Kinematic Viscosity at 210° F.                                                                 5.88                                                  Heat of Combustion, BTU/lb.                                                                           19,064                                                Molecular Weight        357                                                   Metal Analysis, ppm                                                           Copper                  0.2                                                   Iron                    0.6                                                   Nickel                  0.1                                                   Vanadium                0.3                                                   Refractive Index at 70° C.                                                                     1.4879                                                Density by Pycnometer at 70° C., g/cc                                                          0.8751                                                Distillation            D1160                                                 IBP                     502                                                    5                      610                                                   10                      646                                                   20                      716                                                   30                      724                                                   40                      756                                                   50                      786                                                   60                      815                                                   70                      843                                                   80                      873                                                   90                      909                                                   95                      930                                                   ______________________________________                                    

As has already been mentioned, the catalyst of this invention is highlyattrition resistant. The following illustrates this.

Determination of Attrition Index

7 cc of catalyst in a 1 in. i. d. "U" tube is contacted with an air jetformed by passing humidified (60%) air at 21 liters/min. through a 0.07in. diameter nozzle. The attrition phase is performed in the Rollerapparatus and fines in the 0-14μ (nominal) range are removed as formedand caught in a paper collection thimble. At the conclusion of theattrition phase, fines are recombined with residue and the particle sizedetermined; the incremental weight of the collection thimble is added tothe 0-20μ fraction. Particle size in all cases is determined withmicromesh screens in a Sonic Sifter analyzer.

The attrition index is defined as the increase in the fines fraction(0-20μ) caused by the attrition phase: ##EQU1## Attrition indexes forother fractions (e.g. the 0-30μ or the 0-40μ fractions) can bedetermined similarly, but generally show the same behavior as 0-20μindexes. We have found it necessary to use the particle size of thefresh (or as-received) catalyst as the reference. Calcination of thecatalyst in a dish leads to an apparent loss of fines, probably byinteraction of particles ("sticking"). The original particle size iseffectively reestablished in the attrition phase.

The catalyst of this invention had an attrition index (0-20μ) of 0.3.The attrition indexes of six different commercially available catalystsranged from a low of 3.0 up to 17.0. The commercial catalyst also had acrystalline aluminosilicate present as the active member. All attritionindexes are based on fresh catalyst particle size in all cases.

We claim:
 1. A cracking catalyst made by a method comprising the stepsof:(1) nozzle-mixing of an acid alum stream with a second streamcomprising sodium silicate, alkali metal hydroxide and suspended fines;(2) forming droplets of the resulting sol and causing them to gel; (3)exchanging the gel by contacting same, in order, with (a) an ammoniumsalt solution, (b) an aluminum salt solution and (c) a rare earth saltsolution; (4) washing with water; (5) homogenizing; (6) spray drying;(7) impregnating with rare earth ions; and (8) drying.
 2. The catalystof claim 1 wherein said fines are selected from the group consisting ofcrystalline aluminosilicate zeolites, alumina and clays.
 3. The catalystof claim 1 wherein said droplets range in size from about 0.1 mm toabout 15 mm.
 4. The catalyst of claim 1 wherein said fines includes acrystalline aluminosilicate zeolite comprising from about 5 to about 30%by weight.
 5. The catalyst of claim 1 wherein in step (3) at least 60%of the original cation is removed.
 6. The catalyst of claim 4 whereinsaid zeolite is rare earth exchanged zeolite Y.
 7. An improved method ofpreparing a cracking catalyst comprising the steps of:(1) nozzle-mixingof an acid alum stream with a second stream comprising sodium silicate,alkali metal hydroxide and suspended fines; (2) forming droplets of theresulting sol and causing them to gel; (3) washing with water; (4)homogenizing; (5) spray drying; (6) impregnating with rare earth ions;and (7) drying;the improvement whereby the gel is exchanged followingits formation by contacting same, in order, with (a) an ammonium saltsolution, (b) an aluminum salt solution and (c) a rare earth saltsolution.
 8. The method of claim 7 wherein said fines are selected fromthe group consisting of crystalline aluminosilicate zeolites, aluminaand clays.
 9. The method of claim 7 wherein said droplets range in sizeof from about 0.1 mm to about 15 mm.
 10. The method of claim 7 whereinsaid fines includes a crystalline aluminosilicate zeolite comprisingfrom about 5 to about 30% by weight.
 11. The method of claim 7 whereinin step (3) at least 60% of the original cation is removed.
 12. Themethod of claim 10 wherein said zeolite is rare earth exchanged zeoliteY.